Leopold Lojka (1886-1923) was the driver's name, He actually saved the Duke's life from the first attempted assassination, Leopold noticed the grenade and responded instantly, meaning the grenade instead landed behind the Duke's car.

It's not his fault even remotely that the Duke got killed, it's actually the higher-ups fault, see, a new route for safety and to allow the duke to visit the wounded in hospital was planned, but the complete bunch of higher-up idiots forgot to tell THE PERSON DRIVING THE CAR that the route had changed.

So Leopold continued to follow the original route, Franz then told Leopold that he was going the wrong way, so Leopold, understandably confused asked where he was meant to go, Leopold was still driving at this point, Franz then told him to stop the car right now and reverse, so Leopold did, then, one of the assassins spotted the duke and fired at the now halted car.

If Leopold had never been told to stop, the duke wouldn't have died. If Leopold had been told about the route change earlier, the Duke also wouldn't have died.

Higher-ups realized their mistake, and Leopold was instead rewarded for his actions which saved the Duke's life from the first attempt, Leopold then went on to buy a bar with the reward money, and spent the rest of his peaceful life as an innkeeper.